1. Field of the Invention
The present invention relates to an automatic embroidering machine, and more particularly to a device for detecting a breaking of a thread while an embroidering machine carries out a stitching operation in accordance with a predetermined program, and repairing of the thread breaking in response to the detection.
2. Description of the Prior Art
In a known automatic embroidering machine, when the thread is broken, the stitching is instantly stopped on detecting the breaking of the thread, and after repairing it the embroidering is again started from an embroidering data following the data where the thread was broken. Therefore, embroidering continuation was unsightly, or the data of a few stitchings were often missing. Further, due to erroneous detection, the stitching was sometimes stopped notwithstanding the fact that the thread did not break.
To remove such defects, Japanese Patent Publication No. 58,584/86 has proposed that the detection of the thread breaking is performed over several stitchings, and each of them is regarded as a breaking, and the embroidering is again started from a position before a first breaking so as to prevent unsightly embroidering continuation, ravelling or erroneous stopping.
Since the instantaneous stopping on the first detection is made against an inertia of the running mechanism of the sewing machine, the sewing machine is stopped after several stitchings. When the thread is broken, false or empty stitchings are made, and the re-start is begun after the false stitchings.
If the breaking is caused by the thread twisting about a needle, the needle will be destroyed by moving of a fabric frame.
By forming the false stitchings, the fabric is prone to spoil an embroidering finish.